Quantitative sensory testing

An adaptive procedure for routine measurement of light-touch sensitivity threshold

Quantitative sensory testing with Semmes-Weinstein monofilaments suffers from several pitfalls. Our aims were to assess the reliability of these filaments for touch-pressure threshold detection, develop and validate a rapid and accurate procedure for measurements at the bedside, and establish normative data. After calibration of the monofilaments, an adaptive staircase algorithm was validated and used to establish normative data in healthy subjects. Calibration showed significant differences between manufacturer- and investigator-produced data. The relative humidity significantly affected the force exerted by the filaments. The adaptive procedure showed good accuracy and substantial time-saving. Touch-pressure thresholds showed significant gender differences (mean +/- 2 SD for females/males: 2.82-12.3/3.09-17.78 g/mm(2)). The influence of body site and age is small. Accurate use of Semmes-Weinstein monofilaments requires prior calibration, correction for humidity, and use of a validated procedure. In this study we provide normative data that can be used with our algorithm.

Influence of age on thermal thresholds, thermal pain thresholds, and reaction time

The main goals of this study were to investigate the effect of age on thermal and thermal pain thresholds and reaction time, and to analyze the influence of age-related changes in reaction time on thermal and thermal pain thresholds. Thermal thresholds (warm/cold) and thermal pain thresholds (hot/cold) were evaluated by the method of limits. Visual reaction time was evaluated in a similar way by a customized computer program. In total, 274 normal subjects (23-87 years old) were recruited. Thermal thresholds, thermal pain thresholds, and reaction time were all related to age. While warm and cold thresholds and cold pain thresholds increased with age, hot pain thresholds decreased with age. The age-related change in reaction time was insufficient to explain the age-related changes in thermal and thermal pain thresholds. In conclusion, age affects thermal and thermal pain thresholds independently of reaction time.

Quantitative test for sensory hand symptoms based on mechanoreceptor-specific vibrotactile thresholds

A vibrotactile test for assessing the presence or absence of sensory symptoms in the hand has been developed from thresholds believed mediated by Merkel disks and Meissner corpuscles at the fingertips. It is constructed from the summed differences between the thresholds recorded at the fingertip of an individual and the mean values of the threshold for healthy persons at the same stimulation frequencies. The summed normalized threshold shift, TS(Sum(SD)), is shown to be related to reports by subjects of numbness and pain using three statistical tests for evaluating the significance of associations in 2x2 contingency tables. The small number of subjects (15) restricts direct calculation of a fence value for TS(Sum(SD)), t, between the presence and absence of symptoms: accordingly, interpolation between calculated t values has been performed graphically. A common range of t values can be identified that is judged significantly by each statistical test (3.3<or=t<3.9 for numbness; 3.6<or=t<4.1 for pain). The range encompasses the boundary previously identified between "normal" and "abnormal" vibrotactile thresholds, that is, thresholds for which the (two-sided) probability of occurrence in the hands of healthy persons is p approximately 0.05.

Etiology of small-fiber neuropathy

The aim of this study was to evaluate the etiology in a group of 84 patients with painful sensory neuropathy with predominant small-fiber dysfunction (54 men and 30 women, median: 58; range: 25-83 years) recruited from a population of the South Moravian region of the Czech Republic. Involvement of small nerve fibers was verified by abnormal thermal thresholds and/or reduced intraepidermal nerve fiber densities. Motor signs or symptoms or significant clinical signs of sensory large-fiber involvement were exclusionary; 33 patients, however, had sensory nerve conduction abnormalities. For comparison, the prevalence of risk factors was assessed in a group of 47 asymptomatic age- and sex-matched controls (30 men and 17 women, median: 59; range: 29-85 years). The multivariate regression model disclosed that diabetes mellitus (odds ratio [OR] = 4.08), chronic alcoholism (OR = 5.31), and serum cholesterol levels (OR = 4.51) were the only parameters independently associated with small-fiber involvement. No possible etiology was detected in 19 patients (22.6%). In conclusion, the spectrum of risk factors and proportion of idiopathic cases in geographically defined small-fiber polyneuropathy sample is similar to that referred in large-fiber polyneuropathy.

Pain sensitivity in major depression and its relationship to central serotoninergic function as reflected by the neuroendocrine response to clomipramine

Several studies reported a decreased pain sensitivity in patients with depression, but the underlying neurobiological mechanisms of this phenomenon are unclear. While there is extensive evidence that the serotoninergic system plays a key role in pain modulation, especially in pain inhibitory mechanisms via descending pathways, as well as in the pathophysiology of depression, no study so far has examined its potential relevance in mediating the alteration of pain processing. The present study addresses the question of whether indices of serotoninergic dysfunction, as investigated by a neuroendrocine challenge paradigm, are related to pain sensitivity. Nineteen drug-free inpatients with unipolar major depression underwent a neuroendocrine challenge test by measuring cortisol and prolactin in response to intravenously administered clomipramine (12.5mg). Heat/cold pain thresholds, warmth/cold detection thresholds, measures of current pain complaints and mood were assessed the day before and three day after challenge procedure. When patients were classified in subgroups based on a median split of their cortisol response values, the low-responsive group showed significantly elevated heat pain thresholds and nearly significantly elevated cold pain thresholds compared to the high-responsive group. No such group differences were found with regard to somatosensory thresholds, measures of pain complaints and mood. Subgrouping on the basis of prolactin responsiveness did not reveal significant differences in any parameter. In summary, a decreased pain sensitivity was demonstrated in patients characterized by a reduced neuroendocrine responsiveness to clomipramine, suggesting an involvement of serotoninergic dysfunction underlying altered pain perception in depression.

A new method to measure vaginal sensibility

INTRODUCTION

Vaginal surgery may affect sexual function both positively and negatively. Possibly, negative consequences of surgical interventions on sexuality may be caused by reduced sensibility of the vaginal wall.

AIMS

To develop a new method to measure vaginal sensibility.

METHODS

We developed a technique to measure the sensibility of the vaginal wall consisting of a St Marks electrode on a gloved index finger, with a stimulating electrode mounted at the tip. Measurements were performed in four different target areas (caudal and cranial, posterior and anterior) by two independent female researchers in a random order. Subjects were 12 healthy women.

RESULTS

The intra-observer reproducibility of both researchers was almost perfect (Pearsons-Rho correlation coefficient 0.77-0.96 < 0.001). The inter-observer reproducibility was moderate (Pearsons-Rho correlation coefficient 0.39-0.49). Both researchers measured increased sensibility in the cranial posterior vaginal wall relative to the cranial anterior vaginal wall, but for all measurements, researcher 2 obtained higher sensibility ratings than researcher 1. In addition, researcher 2 found a decreased sensibility in the cranial anterior vaginal wall for women not using oral contraceptives. Phase of the menstrual cycle did not influence vaginal sensibility.

CONCLUSION

We developed a new instrument to measure vaginal sensibility. The instrument has excellent intra-observer reproducibility. This method is sufficiently sensitive so as to differentiate between anterior and posterior cranial vaginal wall sensibility, but outcome differs as a function of researcher. Further evaluation of the clinical use of this method is needed, provided that measurements are performed by the same researcher.

Sensory perception thresholds in men with chronic pelvic pain syndrome

OBJECTIVES

To compare sensory thresholds in different nerve-fiber types in men with chronic pelvic pain syndrome (CPPS) and healthy controls, using thermal sensory testing and measuring current perception thresholds (CPT).

METHODS

We enrolled 22 men with CPPS and 20 healthy control participants. We determined the thermal sensory perception thresholds of C and Adelta nerve fibers on the perineum and left posterior thigh. To test CPT, we used sine wave electrical stimulation at 5, 250, and 2000 Hz, resulting in the selective depolarization of small unmyelinated C fibers, small myelinated Adelta, and large myelinated Abeta fibers, respectively. We bilaterally tested the hypothenar surface of the palms, medial parts of soles, midshaft of penis, and 1 site in the midperineum, for a total of 7 sites.

RESULTS

The mean age of men with CPPS was similar to that of controls [42.8 (standard deviation, 9.4) and 40.4 (standard deviation, 13.2) years, respectively, P = .548]. There was no significant difference between the 2 groups for thermal perception thresholds in both the perineum and left thigh (P >.05). There was also no difference between the 2 groups for CPT values of all 3 frequencies of stimuli in each area tested (P >.05 for all comparisons).

CONCLUSIONS

The absence of sensory threshold differences between men with CPPS and controls, with either thermal stimulation of C and Adelta fiber afferents or electrical stimulation of C, Adelta, and Abeta fiber afferents, discounts the existence of a peripheral neuropathy as a cause for pain in men with CPPS.

Electric toothbrush application is a reliable and valid test for differentiating temporomandibular disorders pain patients from controls

BACKGROUND

Current methods for identifying patients with pain hypersensitivity are sufficiently complex to limit their widespread application in clinical settings. We assessed the reliability and validity of a simple multi-modal vibrotactile stimulus, applied using an electric toothbrush, to evaluate its potential as a screening tool for central sensitization.

METHODS

Fourteen female temporomandibular disorders (TMD) subjects with myofascial pain (RDC/TMD Ia or Ib) and arthralgia (RDC/TMD IIIa) were compared to 13 pain-free controls of matched age and gender. Vibrotactile stimulus was performed with an electric toothbrush, applied with 1 pound pressure for 30 seconds in four locations: over the lateral pole of the temporomandibular joint, masseter, temporalis, and mid-ventral surface of forearm. Pain intensity (0-10) was recorded following the stimulus at 0, 15, 30, and 60 seconds. Test-retest reliability was assessed with measurements from 8 participants, taken 2-12 hours apart. Case versus control differentiation involved comparison of area under the curve (AUC). A receiver operating characteristic (ROC) curve was used to determine cutoff AUC scores for maximum sensitivity and specificity for this multi-modal vibrotactile stimulus.

RESULTS

Test-retest reliability resulted in an ICC of 0.87 for all 4 pooled sites. ROC-determined AUC cutoff scores resulted in a sensitivity of 57% and specificity of 92% for all 4 pooled sites.

CONCLUSION

The electric toothbrush stimulus had excellent test-retest reliability. Validity of the scores was demonstrated with modest sensitivity and good specificity for differentiating TMD pain patients from controls, which are acceptable properties for a screening test.

Altered quantitative sensory testing outcome in subjects with opioid therapy

Preclinical studies have suggested that opioid exposure may induce a paradoxical decrease in the nociceptive threshold, commonly referred as opioid-induced hyperalgesia (OIH). While OIH may have implications in acute and chronic pain management, its clinical features remain unclear. Using an office-based quantitative sensory testing (QST) method, we compared pain threshold, pain tolerance, and the degree of temporal summation of the second pain in response to thermal stimulation among three groups of subjects: those with neither pain nor opioid therapy (group 1), with chronic pain but without opioid therapy (group 2), and with both chronic pain and opioid therapy (group 3). We also examined the possible correlation between QST responses to thermal stimulation and opioid dose, opioid treatment duration, opioid analgesic type, pain duration, or gender in group 3 subjects. As compared with both group 1 (n=41) and group 2 (n=41) subjects, group 3 subjects (n=58) displayed a decreased heat pain threshold and exacerbated temporal summation of the second pain to thermal stimulation. In contrast, there were no differences in cold or warm sensation among three groups. Among clinical factors, daily opioid dose consistently correlated with the decreased heat pain threshold and exacerbated temporal summation of the second pain in group 3 subjects. These results indicate that decreased heat pain threshold and exacerbated temporal summation of the second pain may be characteristic QST changes in subjects with opioid therapy. The data suggest that QST may be a useful tool in the clinical assessment of OIH.

Evidence of persistent central sensitization in chronic headaches: a multi-method study

The aim of this study was to investigate central sensitization (CS) in chronic headaches and compare this phenomenon between chronic migraine (CM) and chronic tension-type headache (CTTH). We recruited 69 patients with chronic headaches and 18 control subjects. Questionnaires of headache history, allodynia and the Hospital Anxiety and Depression scale were administered. We recorded thresholds for pinprick and pressure pain, blink (BR) and nociceptive flexion reflex (NFR) R3 component coupled with wind-up ratios. Thresholds for pressure and pinprick pain, BR and NFR R3 were lower and wind-up ratios higher in patients. No differences of CS parameters between CM and CTTH were observed. CS is persistent and prevalent in patients with various types of chronic headache. CS levels are unrelated to the predominant side of pain, disease duration or depression. Neither is CS related to the headache type, suggesting similar mechanisms of headache chronification and chronicity maintaining and possibly explaining clinical similarity of various forms of chronic headache.

Determinants of thermal pain thresholds in normal subjects

OBJECTIVE

Measurement of thermal pain thresholds is an essential part of quantitative sensory testing (QST). However, databases of QST show limitations due to large inter-individual variations including unreasonably low thresholds for thermal pain, lack of data on intra-individual variations over time and on the subjects' perception at threshold. This study sought to reduce inter-individual variations, investigated the reproducibility of measurements of thermal pain thresholds and included evaluation of thermally induced perceptions.

METHODS

Thermal pain thresholds were investigated in 20 healthy subjects over three weeks using two protocols, one of which differed in making the subjects familiar with the likely range of applied temperatures beforehand. Both protocols included subjective ratings of pain and temperature perception at the pain thresholds.

RESULTS

Data obtain using both protocols showed large inter-individual variations, but small intra-individual variations of pain thresholds over time as well as good feasibility and reproducibility of subjects' ratings at threshold.

CONCLUSIONS

Previous experience of test stimuli has no influence on the variability of thermal pain thresholds. However, measurement of thermal pain thresholds showed good reproducibility over time. Evaluation of perception at thresholds provided further reproducible data.

SIGNIFICANCE

Further approaches are needed to reduce variability of thermal pain thresholds; however, good reproducibility of thermal pain thresholds and thermally induced perceptions warrants consideration of their use in larger longitudinal studies.

Thermosensitivity in a reconstructed microtic ear

The aim of this study was to evaluate thermo-thresholds in autologous reconstructed microtic ears. Nineteen patients with unilateral microtia were investigated no less than two years after the last operation (3.6+/-1.7 years). Their normal corresponding ear acted as controls. Eight healthy children were also investigated to illustrate technical differences between measuring the two sides. Thermal sensitivity was tested quantitatively using a SENSELab MSA Thermotest. The skin temperature was also tested. Three different areas of the ear were examined: the lobe, the antihelix, and the helix. The reconstructed ear had a significantly higher skin temperature for all investigated areas compared with the normal ear (reconstructed ear 30.2+/-1.2 degrees C, normal ear 28.6+/-0.9 degrees C). For the controls there were no significant differences in any area. For the patients there were small differences in perception of cold between the reconstructed and the normal ear. There were significant differences in the antihelix region and the helix in heat perception in the reconstructed ear compared with the normal one (helix reconstructed ear 43.9+/-3.8 degrees C, helix normal ear 38.3+/-3.0 degrees C, antihelix reconstructed ear 39.9+/-3.0 degrees C, antihelix normal ear 36.4+/-1.7 degrees C). The reconstructed ear had a changed thermosensitivity, but there did not seem to be any clinical disadvantages.

Abnormal heat and pain perception in remitted heroin dependence months after detoxification from methadone-maintenance

Patients receiving methadone maintenance therapy (MMT) for opiate dependence have altered nociception, complicating analgesic treatment. Increasing numbers of patients are choosing opiate-free treatment programs, yet data on the course of this abnormality months after detoxification from methadone is contradictory and based exclusively on cold pressor experiments. Heat and pain thresholds were measured by quantitative sensory testing (QST) in 23 subjects with heroin dependence in full, sustained remission months after detoxification from methadone and 27 healthy non-drug using controls. Self reports of pain intensity and unpleasantness were also collected. Test scores were compared across groups and correlated with measures of drug use history. There were significant differences between remitted opiate-dependent subjects and controls on the measures of heat threshold (38.83 vs. 35.96; Mann-Whitney U=177.5, p=0.006), and the measure of pain threshold (48.73 vs. 47.62; Mann-Whitney U=217.5, p=0.043). There was no correlation of any measure of drug use history with the heat or pain experience. Abstinent, formerly opioid-dependent patients continue to demonstrate abnormal noxious perception months after detoxification from methadone.

Comparison of perception threshold testing and thermal-vibratory testing

Current perception threshold testing (CPT) is thought to selectively activate and measure three types of afferent nerves. However, it has not been standardized or compared with better-studied methods of sensory testing. Our objectives were to determine the relationship between CPT (2000 Hz, 250 Hz, 5 Hz) and quantitative sensory testing (QST) using vibratory and heat thresholds, and to assess the test-retest reliability of both methods. Twenty-seven healthy women were enrolled. Each woman underwent CPT and QST on the volar part of the arm. Sensory thresholds were determined by the method of limits; 20 women underwent repeated CPT testing and QST after 1 week to determine test-retest reliability. Thermal thresholds were moderately correlated with CPT at 5 Hz (rho = 0.49, P = 0.009), as were vibratory thresholds and CPT at 2000 Hz (rho = 0.5, P = 0.008). In contrast to CPT measurements, warm and vibratory and cold thresholds were correlated 1 week apart (rho = 0.73, P = 0.0001; rho = 0.83, P = 0.0001; and rho = 0.47, P = 0.0037, respectively). CPT testing and QST seem to be measuring similar afferent nerve-fiber populations, but QST has better test-retest reliability than CPT testing, justifying its role in clinical or research studies.

Pudendal entrapment as an etiology of chronic perineal pain: Diagnosis and treatment

AIMS

This study was conducted to evaluate pudendal entrapment as an etiology of chronic pain, a diagnostic protocol for pudendal entrapment, and clinical response to surgical decompression.

METHODS

A case series of 58 consecutive patients with a diagnosis of pudendal entrapment, based on clinical factors, neurophysiologic studies, and response to pudendal nerve infiltrations, is described. All patients were refractory to other treatment modalities. Patients were assessed before and after surgical decompression: degree of pain was assessed by visual analog scale (VAS) score, percent global overall improvement, and improved function and quality of life before surgery and 12 months or longer after surgery.

RESULTS

The primary presenting feature was progressive, chronic, intractable neuropathic pain in the perineum (ano-rectal and/or urogenital) that worsened with sitting. Other symptoms included urinary hesitancy, frequency, urgency, constipation/painful bowel movements, and sexual dysfunction. After surgical decompression, 35 (60%) patients were classified as responders, based on one of the following three criteria: a greater than 50% reduction in VAS score, a greater than 50% improvement in global assessment of pain, or a greater than 50% improvement in function and quality of life.

CONCLUSIONS

Pudendal entrapment can be a cause of chronic, disabling perineal pain in both men and women. Since symptomatic patients seek medical care from many different medical specialists, a reliable diagnostic protocol should be established. For patients refractory to conventional interventions, surgical decompression of the pudendal nerve can improve pain-related symptoms and disability. With ongoing work on this subject, which is a difficult disorder to accurately diagnose and treat, a better awareness of pudendal entrapment across specialties will emerge.

Vagal damage enhances polyneuropathy pain: additive effect of two algogenic mechanisms

While the major pain generation in polyneuropathy is in the somatic peripheral nerves, pathologies at visceral nerves might be involved as well. Decreased vagal afferent activity is known to disinhibit pain perception, and therefore might contribute to pain in polyneuropathy. In this study we explored this potential contribution by employing a rat model of vincristine (VCR)-induced pain after sub-diaphragmatic vagotomy (SDV). Forty rats were divided into 4 groups: VCR, SDV, VCR+SDV and controls. Each rat underwent a variety of pain-related behavioral tests including assessment of spontaneous pain, allodynia and hyperalgesia to thermal and mechanical stimuli. We found that VCR+SDV rats had enhanced painful neuropathy compared to VCR alone, expressed as: (1) earlier development of central sensitization: at the first week in rats that underwent SDV+VCR (p<0.0001) and only at the second week in rats injected with VCR alone (p<0.0001), (2) increased incidence of spontaneous pain behavior (p=0.0036), (3) spreading of the spontaneous pain behavior to the forelimbs, (4) higher mechanical dynamic allodynia (tendency, p=0.08) and (5) augmentation of the response to repetitive painful and non-painful mechanical stimuli (p<0.001). Thus, decreased vagal activity aggravates both the severity and the time course of painful polyneuropathy. Therefore, the two mechanisms add to each other in generating the pain picture.

Effects of total sleep deprivation in major depression: overnight improvement of mood is accompanied by increased pain sensitivity and augmented pain complaints

OBJECTIVE

Major depressive disorder (MDD) is associated with more pain complaints and an altered pain perception. Studies regarding the longitudinal relationship between depressive symptoms and pain processing have rarely been performed and have produced inconsistent results. To clarify how short-term alleviation of depressive mood is linked to changes in pain processing, the effect of sleep deprivation (SD) on pain and somatosensory thresholds, pain complaints, and mood was investigated in MDD patients.

METHODS

Nineteen drug-free inpatients with Diagnostic and Statistical Manual of Mental Disorders, fourth edition, diagnosis of MDD were investigated for 3 weeks. All patients received cognitive-behavioral therapy and were randomized to obtain either additional SD therapy (six nights of total SD, separated by recovery sleep) or no SD therapy (control group). Heat/cold pain thresholds, warmth/cold thresholds, measures of current pain complaints, and mood were assessed the evening before and the morning after SD as well as before and after a normal night sleep in the control group. Long-term changes of depressive symptomatology were assessed by weekly mood ratings.

RESULTS

Both treatment groups improved markedly in mood over the 3-week treatment period. SD regularly induced a moderate but statistically nonsignificant overnight improvement of mood, which was abolished by recovery sleep. Compared with the control condition, SD significantly decreased heat pain thresholds and nearly significantly cold pain thresholds; SD significantly augmented pain complaints the next morning. No such effects were observed for somatosensory thresholds.

CONCLUSIONS

SD induced differential short-term effects on mood and pain, with the patients being less depressed but more pain vulnerable.

Lung-uptake and -washout of MIBG in sarcoidosis

BACKGROUND

The aim of this study was to evaluate the uptake and -washout of I-123 meta-iodobenzylguanidine (MIBG), reflecting norepinephrine metabolism, in the lungs in patients with sarcoidosis.

METHODS

Lung I-123 MIBG kinetics was assessed in 43 patients with sarcoidosis. The range of disease duration was 1-16 years (median: 3 years). Thirteen patients had radiographic stage 0-I, 30 patients had radiographic stage II-IV. Serological clinical parameters and small fibre neuropathy, as assessed by temperature threshold testing (TTT) were measured in 39/43 patients. 31/39 patients had an abnormal TTT. Eleven healthy controls participated in this study. Both dual head planar and dual headed SPECT images of the thoracic regions were made. The uptake of I-123 MIBG and the washout percentage were calculated in sarcoidosis patients and compared with the healthy persons.

RESULTS

Lung I-123 MIBG uptake in patients with sarcoidosis did not differ from controls. The lung washout of I-123 MIBG was significantly (p<or=0.01) decreased in sarcoidosis. Remarkably this was most clearly seen in patients with an abnormal TTT and in patients with more advanced radiographic pulmonary involvement (radiographic stages II-IV) but not in patients with decreased lung function (FVC<80% or DLCO<80%).

CONCLUSION

The inflammatory process of the lungs in sarcoidosis seems not to affect pulmonary vasculature. In sarcoidosis decreased lung washout of I-123 MIBG might, at least partly, be explained by sympathetic autonomic nerve dysfunction. Future studies are needed to explore the clinical relevance of this observation.

Diagnostic validity of epidermal nerve fiber densities in painful sensory neuropathies

In this prospective study, intraepidermal nerve fiber densities (IENFD) and subepidermal nerve plexus densities (SENPD) were quantified by immunostaining in skin punch biopsies from the distal calf in 99 patients with clinical symptoms of painful sensory neuropathy and from 37 age-matched healthy volunteers. The clinical diagnosis was based on history and abnormal thermal thresholds on quantitative sensory testing (QST). In patients with neuropathy, IENFD and SENPD were reduced to about 50% of controls. Elevated warm detection thresholds on QST correlated with IENFD but not with SENPD. Using receiver-operating characteristic (ROC) curve analysis of IENFD values, the diagnostic sensitivity for detecting neuropathy was 0.80 and the specificity 0.82. For SENPD, sensitivity was 0.81 and specificity 0.88. With ROC analysis of both IENFD and SENPD together, the diagnostic sensitivity was further improved to 0.92. The combined examination of IENFD and SENPD is a highly sensitive and specific diagnostic tool in patients suspected to suffer from painful sensory neuropathies but with normal values on clinical neurophysiological studies.

Enhanced skin blood flow and sensitivity to noxious heat stimuli in papulopustular rosacea

BACKGROUND

Although patients with rosacea often complain of increased skin sensitivity, there has been no quantitative sensory testing of this phenomenon. Furthermore, cutaneous blood flow in these patients has not been assessed using state-of-the-art laser Doppler imaging (LDI).

OBJECTIVES

To assess heat pain thresholds and skin blood flow using quantitative thermal sensory testing and LDI in patients with untreated rosacea.

METHODS

Of the total 24 subjects enrolled, 8 had papulopustular rosacea (PPR), 8 had erythematotelangiectatic rosacea (ETR) and 8 were control subjects. Subjective burning perception, heat pain threshold, skin blood flow, and skin temperature was assessed in all subjects. In the ETR and PPR groups, two areas were compared: affected and nonaffected.

RESULTS

Heat pain thresholds of areas affected by rosacea were lower than those of nonaffected areas. In addition, subjective burning perception was increased in rosacea patients when compared with control subjects. Although PPR-affected skin had elevated skin blood flow when compared with nonaffected skin, this was not significant for ETR-affected skin.

LIMITATIONS

The small number of subjects enrolled was the main limitation.

CONCLUSION

This study showed enhanced sensitivity to noxious heat stimuli in rosacea-affected skin, which was more prominent in the PPR group.

Botulinum toxin A does not alter capsaicin-induced pain perception in human skin

A genuine peripheral antinociceptive and anti-inflammatory effect of Botulinum neurotoxin type A (BoNT/A) has been proposed but could not be demonstrated in humans so far. Therefore, 100 mouse units of Botulinum toxin A (Dysport) and placebo were injected in a double blind paradigm in defined skin areas of 50 subjects. At baseline and after 4 and 8 weeks allodynia was induced in the skin areas with capsaicin ointment. Heat and cold pain threshold temperatures were measured with quantitative sensory testing, and threshold intensities upon electrical stimulation with a pain specific surface electrode were determined. No BoNT/A related differences in pain perception were found at any quality. There is neither a direct peripheral antinociceptive effect nor a significant effect against neurogenic inflammation of BoNT/A in humans.

Clinical and experimental pain perception is attenuated in patients with painless myocardial infarction

BACKGROUND

The lack of pain alarm in painless myocardial infarction (MI) leads to increased morbidity and mortality, since patients do not seek medical treatment in a timely manner. We aimed to explore whether reduced systemic pain perception in response to experimental stimuli and pain related personality variables characterizes painless MI patients.

METHODS

Level of chest pain intensity was assessed by numerical scale, range from 0 (no pain) to 100 (maximal pain). Heat pain threshold, magnitude estimation of supra-threshold phasic and tonic painful stimuli as well as anxiety and pain catastrophizing scores were assessed in 92 acute MI patients; 67 with and 25 without chest pain, respectively. All experimental stimuli were performed by Thermal Sensory Analysis (TSA) and applied to the right forearm.

RESULTS

Greater intensity of chest pain scores was inversely correlated with lower pain threshold (r=-0.417, p<0.001), and directly associated with higher pain scores in response to the heat pain (r=0.354, p=0.002). Patients with painful MI demonstrated lower pain threshold (41.9+/-3.6 degrees C vs. 44.9+/-3.8 degrees C, p=0.001) and higher catastrophizing level (10.6+/-12.0 vs. 5.4+/-8.8, p=0.032). Logistic regression analysis revealed that older age and lower pain scores in response to supra-threshold painful stimuli were associated with greater risk for painless MI. The demographic variables, history of ischemic heart, risk factors for coronary artery disease, ST-T segment changes on ECG and troponin levels were similar in both groups.

CONCLUSIONS

This study suggests that reduced systemic pain perception as well as cognitive personality variables play an important role in the etiology of painless MI.

Development of a novel method to determine human current perception threshold

This paper reports a novel instrument for human current perception threshold (CPT) measurement. An objective galvanic skin response (GSR) method is employed to monitor subject's response to quantitative stimuli. Experimental results show that new system is more objective and easy to operate in comparison with conventional quantitative sensory testing systems.

Considerations in evaluating new treatment alternatives following peripheral nerve injuries: A prospective clinical study of methods used to investigate sensory, motor and functional recovery

The current problem finding reliable and objective methods for evaluating results after peripheral nerve repair is a challenge when introducing new clinical techniques. The aim of this study was to obtain reference material and to evaluate the applicability of different tests used for clinical assessment after peripheral nerve injuries. Fifteen patients with a history of complete median nerve transsection and repair, and 15 healthy volunteers were included. Each subject was investigated using a battery of conventional and new tests for functional, sensory and motor recovery including questionnaires, clinical evaluations, neurophysiological and physiological findings. The results were statistically analysed and comparisons were made within the patient group and between patients and healthy volunteers using a 'per protocol' and an 'intention to treat' approach. Criteria for success were stipulated in order to be able to judge the usefulness of each method. The results showed that 19 of 34 variables, representing six of 16 methods, were not able to fulfil the criteria and were thus questionable for the evaluations of nerve repair in a clinical trial setting. However, 2pd, sensory recovery according to the non-modified British Medical Research Council, sensory neurography, manual muscle test, electromyography, questionnaires (i.e. DASH and the 4 question form) and performance tests (i.e. AMPS and Sollerman's subtests 4 and 8) did fulfil the criteria defined for being useful.

Quantitative sensory testing of patients with long lasting Patellofemoral pain syndrome

BACKGROUND

Anterior knee pain, diagnosed as Patellofemoral Pain Syndrome (PFPS), is one of the most common musculoskeletal problems found in adolescents and young adults. There is no consensus in medical literature concerning the aetiology of the PFPS.

AIMS

To assess by means of Quantitative Sensory Testing (QST) whether patients suffering from long-lasting unilateral PFPS demonstrate somatosensory dysfunction related to afferent fibres from the local pain area.

METHODS

A descriptive non-experimental study with two independent samples, consisting of 25 men and women between 18 and 44 years of age with unilateral PFPS, and a comparable group of 23 healthy subjects. Somedic Thermotest apparatus was used to assess thresholds of thermal perception, and of heat and cold pain thresholds. Von Frey filaments were used to detect tactile sensitivity. Furthermore, quality and intensity of knee pain, symptoms and signs from a clinical neurological examination were recorded.

RESULTS

Decreased sensitivity to tactile stimulation, when tested with von Frey filaments, was demonstrated on both the painful and pain-free knee in subjects with PFPS, compared to the mean between the knees of the control group (p< or =0.001). The mean detection threshold for warmth was increased by 1.9 degrees C (p< or =0.01) in the painful knee, and 1.4 degrees C (p< or =0.01) in the non-painful knee in the PFPS group, compared to the mean of the healthy control group. The mean detection threshold for cold was increased by 1.6 degrees C (p< or =0.01) in the painful knee of the PFPS group, compared to the control group. These findings were supported by clinical sensory tests. No significant differences of mean thermal pain thresholds between the PFPS group and controls were found, and there were no significant differences in mean detection thresholds for warmth, cold or thermal pain thresholds between the painful and the non-painful knees in the PFPS group.

CONCLUSION

This study demonstrated an abnormal sensory function in the painful and non-painful knee in some individuals with long lasting unilateral Patellofemoral Pain Syndrome using Quantitative Sensory Testing supported by clinical neurological examinations. A dysfunction of the peripheral and/or the central nervous system may cause neuropathic pain in some subjects with PFPS.

Quantified sensory abnormalities in early genetically verified transthyretin amyloid polyneuropathy

Transthyretin amyloid neuropathy of type 1 (Swedish-Portuguese type) is an autosomally inherited progressive disease with a Val30Met mutation, causing generalized sensory-motor polyneuropathy. Quantitative sensory testing (QST) quantifies thermal threshold changes in patients with manifest general polyneuropathy, but its applicability at an early clinical stage of a strict biochemically defined disease has not yet been shown. Thermal QST was performed in 23 patients having a positive Val30Met marker and clinical symptoms of peripheral small-fiber neuropathy but normal electrophysiological findings and compared to a reference group of 43 healthy volunteers, both subdivided into age groups < or =45 and >45 years. Significant differences between patients and controls were found at all test sites in both age groups, except for warm thresholds at the medial lower leg in those >45 years. QST thus demonstrated elevated thermal thresholds before the development of electrophysiological abnormalities, which indicate large-fiber involvement. These findings confirm that QST is a useful method for documentation of developing polyneuropathy.

Bedside neuropathy disability score compared to quantitative sensory testing for measurement of diabetic neuropathy in children, adolescents, and young adults with type 1 diabetes

BACKGROUND

While regular yearly screening for diabetic retinopathy and nephropathy is well established in patients with diabetes mellitus, there are no standardized diagnostic tests for diabetic peripheral neuropathy (DPN). In the present study, we compared the bedside neuropathy disability score (NDS) with quantitative sensory testing (QST) for screening for DPN in youth with type 1 diabetes mellitus.

METHODS

One hundred sixty-six patients aged 10 to 34 years (median 21 years) were evaluated for DPN by the NDS and QST. Quantitative sensory testing was also done in 43 healthy, age-matched controls. Diabetic peripheral neuropathy grade by both methods was correlated with disease-related variables.

RESULTS

On QST, the diabetic group had significantly higher mean scores for vibration (P<.001) and warm sensation (P<.01) than controls, and lower scores for cold sensation (P<.05); however, there was a great degree of overlap. The NDS significantly correlated with the vibration threshold, but not with the warm and cold thresholds. The NDS significantly correlated with age at testing, diabetes duration, and long-term and current HbA1c levels (P<.001), and with the presence of microalbuminuria and diabetic retinopathy (P<.001). Analysis of the QST variables yielded significant correlations of vibration and warm sensation with age at testing (P<.001, P<.05, respectively) and of vibration with diabetes duration (P<.001) and retinopathy (P=.05); none of the quantitative tests correlated with glycemic control.

CONCLUSIONS

The stronger association of the NDS with glycemic control and other microvascular complications compared to the perception thresholds, and its shorter time of performance and lack of costly equipment, may make the NDS the preferred method for measuring DPN in this population.

Comparison of clinical evaluation and neurosensory testing in the early diagnosis of superimposed entrapment neuropathy in diabetic patients

Diabetic patients are more susceptible to the development of entrapment neuropathy than nondiabetics. Since these patients suffer from a slowly progressing diabetic polyneuropathy, standard neurosensory and motor tests of nerve function are not sufficient in the diagnosis of superimposed nerve compression. This is most evident in the early stages of compression when quantitative diagnosis is important for making decisions on surgical decompression. We evaluated the validity of computer-assisted pressure-specified sensory device (PSSD) testing in the early detection of superimposed entrapment in diabetic neuropathy in comparison with standard clinical tests. Twenty-five diabetic patients with complaints of peripheral nerve dysfunction were evaluated by clinical tests and PSSD. Out of those, nerve entrapment was detected in 15 patients (60%) (9 in late and 6 in early stage) by neurosensory PSSD testing. Standard clinical tests were confirmative in 33.3% of these cases (44% of late and 16.7% of early stage). Out of 144 evaluated nerves, 50 were diagnosed with entrapment (24 in late and 26 in early stage) using PSSD. Clinically, diagnosis was confirmed in 16% of entrapped nerves (20.8% of late and 11.5% of early stage). Average diabetes duration in patients with entrapment diagnosed using PSSD was significantly shorter than for those diagnosed clinically (4.14 +/- 2.04 vs. 7.2 +/- 1.3, respectively; P = 0.005). Among evaluated factors, mean age and diabetes duration were found to be significantly shorter in patients with entrapment than in those with advanced diffused changes (54.47 +/- 13.07 vs. 67.10 +/- 14.2; P = 0.019 and 5.33 +/- 3.74 vs.14.22 +/- 8.17; P = 0.006; respectively). Our results revealed higher sensitivity of PSSD in comparison with standard clinical tests in the detection of early-stage entrapment in patients with diabetes. To assess accuracy of PSSD in the proper patients' qualification for surgery, further prospective, postoperative studies are needed.

Exploding vs. imploding headache in migraine prophylaxis with Botulinum Toxin A

Migraine headache is routinely managed using medications that abort attacks as they occur. An alternative approach to migraine management is based on prophylactic medications that reduce attack frequency. One approach has been based on local intramuscular injections of Botulinum Toxin Type A (BTX-A). Here, we explored for neurological markers that might distinguish migraine patients who benefit from BTX-A treatment (100 units divided into 21 injections sites across pericranial and neck muscles). Responders and non-responders to BTX-A treatment were compared prospectively (n=27) and retrospectively (n=36) for a host of neurological symptoms associated with their migraine. Data pooled from all 63 patients are summarized below. The number of migraine days per month dropped from 16.0+/-1.7 before BTX-A to 0.8+/-0.3 after BTX-A (down 95.3+/-1.0%) in 39 responders, and remained unchanged (11.3+/-1.9 vs. 11.7+/-1.8) in 24 non-responders. The prevalence of aura, photophobia, phonophobia, osmophobia, nausea, and throbbing was similar between responders and non-responders. However, the two groups offered different accounts of their pain. Among non-responders, 92% described a buildup of pressure inside their head (exploding headache). Among responders, 74% perceived their head to be crushed, clamped or stubbed by external forces (imploding headache), and 13% attested to an eye-popping pain (ocular headache). The finding that exploding headache was impervious to extracranial BTX-A injections is consistent with the prevailing view that migraine pain is mediated by intracranial innervation. The amenability of imploding and ocular headaches to BTX-A treatment suggests that these types of migraine pain involve extracranial innervation as well.

Clinical Presentation, Quantitative Sensory Testing, and Therapy of 2 Patients with Fourth Thoracic Syndrome

OBJECTIVE

The aim of the study was to describe 2 representative cases of patients presenting to an osteopathic pain practice with signs and symptoms consistent with the fourth thoracic (T4) syndrome. In addition, this article reports the application of quantitative thermosensory testing and dynamometer strength testing to confirm associated sensory and motor strength changes. Nonmanipulative therapeutic interventions are reported for the first time.

CLINICAL FEATURES

Two patients experienced paresthesias in all digits of the hands, glove-like numbness of the hands and forearm, weakness (unable to open jars), hand clumsiness, upper extremity coldness, fullness or tightness, deep aching pain, and other signs and symptoms consistent with T4 syndrome. The patients were evaluated using quantitative thermosensory testing and handgrip dynamometry before and after treatment.

INTERVENTION AND OUTCOME

Relief of bilateral arm pain, numbness, and paresthesias occurred after intramuscular injections of 1 to 2 mL of 0.5% bupivacaine at the fourth thoracic paraspinal level. Additional therapy for associated signs and symptoms was provided using an anticonvulsant (gabapentin).

CONCLUSION

The clinical presentation of the patients reported in this article provides a description and additional information regarding T4 syndrome.

Reduced Epidermal Nerve Density Among Hand-Transmitted Vibration-Exposed Workers

OBJECTIVE

The objective of this study was to evaluate ultrastructural changes of epidermal nerve density (END) in workers exposed to hand-transmitted vibration.

METHODS

Ten male subjects with occupational exposure to hand-transmitted tools for 46.9 hours weekly for an average of 6.5 years were included in this study. We performed a skin biopsy from the forearms and compared the END with 10 age- and gender-matched healthy control subjects.

RESULTS

Nine of the 10 subjects had abnormally low END. The END of the exposed workers was significantly lower than the control group (4.1 +/- 2.8 vs 9.0 +/- 4.3 fibers/mm, P = 0.005). The difference remained even after one subject with possible undiagnosed diabetes was not included (4.3 +/- 2.9 vs 9.6 +/- 4.2 fibers/mm, P = 0.005). The reduction of END did not correlate with the abnormality of nerve conduction studies or quantitative sensory testing.

CONCLUSIONS

The reduction of END suggested the involvement of small-diameter nerve fibers among this population, and such a histologic change might either be independent or precede changes of large myelinated nerve fibers.

Contact heat-evoked temporal summation: tonic versus repetitive-phasic stimulation

Temporal summation (TS) is usually evoked by repetitive mechanical or electrical stimuli, and less commonly by tonic heat pain. The present study aimed to examine the TS induction by repetitive-phasic versus tonic heat pain stimuli. Using 27 normal volunteers, we compared the extent of summation by three calculation methods: start-to-end pain rating difference, percent change, and double-logarithmic regression of successive ratings along the stimulation. Subjects were tested twice, and the reliability of each of the paradigms was obtained. In addition, personality factors related to pain catastrophizing and anxiety level were also correlated with the psychophysical results. Both paradigms induced significant TS, with similar increases for the repetitive-phasic and the tonic paradigms, as measured on 0-100 numerical pain scale (from 52.9+/-11.7 to 80.2+/-15.5, p<0.001; and from 38.5+/-13.3 to 75.8+/-18.3, p<0.001, respectively). The extent of summation was significantly correlated between the two paradigms, when calculated by absolute change (r=0.543, p=0.004) and by regression (r=0.438, p=0.025). Session-to-session variability was similar for both paradigms, relatively large, yet not biased. As with other psychophysical parameters, this poses some limitations on TS assessment in individual patients over time. The extent of TS induced by both paradigms was found to be associated with anxiety level and pain catastrophizing. Despite some dissimilarity between the repetitive-phasic and the tonic paradigms, the many similarities suggest that the two represent a similar physiological process, even if not precisely the same. Future clinical applications of these tests will determine the clinical relevance of the TS paradigms presented in this study.